//
// detail/reactive_descriptor_service.hpp
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2022 Christopher M. Kohlhoff (chris at kohlhoff dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//

#ifndef ASIO_DETAIL_REACTIVE_DESCRIPTOR_SERVICE_HPP
#define ASIO_DETAIL_REACTIVE_DESCRIPTOR_SERVICE_HPP

#if defined(_MSC_VER) && (_MSC_VER >= 1200)
# pragma once
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)

#include "asio/detail/config.hpp"

#if !defined(ASIO_WINDOWS) \
 && !defined(ASIO_WINDOWS_RUNTIME) \
 && !defined(__CYGWIN__) \
 && !defined(ASIO_HAS_IO_URING_AS_DEFAULT)

#include "asio/associated_cancellation_slot.hpp"
#include "asio/buffer.hpp"
#include "asio/cancellation_type.hpp"
#include "asio/execution_context.hpp"
#include "asio/detail/bind_handler.hpp"
#include "asio/detail/buffer_sequence_adapter.hpp"
#include "asio/detail/descriptor_ops.hpp"
#include "asio/detail/descriptor_read_op.hpp"
#include "asio/detail/descriptor_write_op.hpp"
#include "asio/detail/fenced_block.hpp"
#include "asio/detail/memory.hpp"
#include "asio/detail/noncopyable.hpp"
#include "asio/detail/reactive_null_buffers_op.hpp"
#include "asio/detail/reactive_wait_op.hpp"
#include "asio/detail/reactor.hpp"
#include "asio/posix/descriptor_base.hpp"

#include "asio/detail/push_options.hpp"

namespace asio {
    namespace detail {

        class reactive_descriptor_service :
                public execution_context_service_base<reactive_descriptor_service> {
        public:
            // The native type of a descriptor.
            typedef int native_handle_type;

            // The implementation type of the descriptor.
            class implementation_type
                    : private asio::detail::noncopyable {
            public:
                // Default constructor.
                implementation_type()
                        : descriptor_(-1),
                          state_(0) {
                }

            private:
                // Only this service will have access to the internal values.
                friend class reactive_descriptor_service;

                // The native descriptor representation.
                int descriptor_;

                // The current state of the descriptor.
                descriptor_ops::state_type state_;

                // Per-descriptor data used by the reactor.
                reactor::per_descriptor_data reactor_data_;
            };

            // Constructor.
            ASIO_DECL reactive_descriptor_service(execution_context &context);

            // Destroy all user-defined handler objects owned by the service.
            ASIO_DECL void shutdown();

            // Construct a new descriptor implementation.
            ASIO_DECL void construct(implementation_type &impl);

            // Move-construct a new descriptor implementation.
            ASIO_DECL void move_construct(implementation_type &impl,
                                          implementation_type &other_impl)

            ASIO_NOEXCEPT;

            // Move-assign from another descriptor implementation.
            ASIO_DECL void move_assign(implementation_type &impl,
                                       reactive_descriptor_service &other_service,
                                       implementation_type &other_impl);

            // Destroy a descriptor implementation.
            ASIO_DECL void destroy(implementation_type &impl);

            // Assign a native descriptor to a descriptor implementation.
            ASIO_DECL asio::error_code
            assign(implementation_type
            & impl,
            const native_handle_type &native_descriptor,
                    asio::error_code
            & ec);

            // Determine whether the descriptor is open.
            bool is_open(const implementation_type &impl) const {
                return impl.descriptor_ != -1;
            }

            // Destroy a descriptor implementation.
            ASIO_DECL asio::error_code
            close(implementation_type
            & impl,
            asio::error_code &ec
            );

            // Get the native descriptor representation.
            native_handle_type native_handle(const implementation_type &impl) const {
                return impl.descriptor_;
            }

            // Release ownership of the native descriptor representation.
            ASIO_DECL native_handle_type
            release(implementation_type
            & impl);

            // Cancel all operations associated with the descriptor.
            ASIO_DECL asio::error_code
            cancel(implementation_type
            & impl,
            asio::error_code &ec
            );

            // Perform an IO control command on the descriptor.
            template<typename IO_Control_Command>
            asio::error_code io_control(implementation_type &impl,
                                        IO_Control_Command &command, asio::error_code &ec) {
                descriptor_ops::ioctl(impl.descriptor_, impl.state_,
                                      command.name(), static_cast<ioctl_arg_type *>(command.data()), ec);
                return ec;
            }

            // Gets the non-blocking mode of the descriptor.
            bool non_blocking(const implementation_type &impl) const {
                return (impl.state_ & descriptor_ops::user_set_non_blocking) != 0;
            }

            // Sets the non-blocking mode of the descriptor.
            asio::error_code non_blocking(implementation_type &impl,
                                          bool mode, asio::error_code &ec) {
                descriptor_ops::set_user_non_blocking(
                        impl.descriptor_, impl.state_, mode, ec);
                return ec;
            }

            // Gets the non-blocking mode of the native descriptor implementation.
            bool native_non_blocking(const implementation_type &impl) const {
                return (impl.state_ & descriptor_ops::internal_non_blocking) != 0;
            }

            // Sets the non-blocking mode of the native descriptor implementation.
            asio::error_code native_non_blocking(implementation_type &impl,
                                                 bool mode, asio::error_code &ec) {
                descriptor_ops::set_internal_non_blocking(
                        impl.descriptor_, impl.state_, mode, ec);
                return ec;
            }

            // Wait for the descriptor to become ready to read, ready to write, or to have
            // pending error conditions.
            asio::error_code wait(implementation_type &impl,
                                  posix::descriptor_base::wait_type w, asio::error_code &ec) {
                switch (w) {
                    case posix::descriptor_base::wait_read:
                        descriptor_ops::poll_read(impl.descriptor_, impl.state_, ec);
                        break;
                    case posix::descriptor_base::wait_write:
                        descriptor_ops::poll_write(impl.descriptor_, impl.state_, ec);
                        break;
                    case posix::descriptor_base::wait_error:
                        descriptor_ops::poll_error(impl.descriptor_, impl.state_, ec);
                        break;
                    default:
                        ec = asio::error::invalid_argument;
                        break;
                }

                return ec;
            }

            // Asynchronously wait for the descriptor to become ready to read, ready to
            // write, or to have pending error conditions.
            template<typename Handler, typename IoExecutor>
            void async_wait(implementation_type &impl,
                            posix::descriptor_base::wait_type w,
                            Handler &handler, const IoExecutor &io_ex) {
                bool is_continuation =
                        asio_handler_cont_helpers::is_continuation(handler);

                typename associated_cancellation_slot<Handler>::type slot
                        = asio::get_associated_cancellation_slot(handler);

                // Allocate and construct an operation to wrap the handler.
                typedef reactive_wait_op <Handler, IoExecutor> op;
                typename op::ptr p = {asio::detail::addressof(handler),
                                      op::ptr::allocate(handler), 0};
                p.p = new(p.v) op(success_ec_, handler, io_ex);

                ASIO_HANDLER_CREATION((reactor_.context(), *p.p, "descriptor",
                        &impl, impl.descriptor_, "async_wait"));

                int op_type;
                switch (w) {
                    case posix::descriptor_base::wait_read:
                        op_type = reactor::read_op;
                        break;
                    case posix::descriptor_base::wait_write:
                        op_type = reactor::write_op;
                        break;
                    case posix::descriptor_base::wait_error:
                        op_type = reactor::except_op;
                        break;
                    default:
                        p.p->ec_ = asio::error::invalid_argument;
                        reactor_.post_immediate_completion(p.p, is_continuation);
                        p.v = p.p = 0;
                        return;
                }

                // Optionally register for per-operation cancellation.
                if (slot.is_connected()) {
                    p.p->cancellation_key_ =
                            &slot.template emplace<reactor_op_cancellation>(
                                    &reactor_, &impl.reactor_data_, impl.descriptor_, op_type);
                }

                start_op(impl, op_type, p.p, is_continuation, false, false);
                p.v = p.p = 0;
            }

            // Write some data to the descriptor.
            template<typename ConstBufferSequence>
            size_t write_some(implementation_type &impl,
                              const ConstBufferSequence &buffers, asio::error_code &ec) {
                typedef buffer_sequence_adapter <asio::const_buffer,
                ConstBufferSequence> bufs_type;

                if (bufs_type::is_single_buffer) {
                    return descriptor_ops::sync_write1(impl.descriptor_,
                                                       impl.state_, bufs_type::first(buffers).data(),
                                                       bufs_type::first(buffers).size(), ec);
                } else {
                    bufs_type bufs(buffers);

                    return descriptor_ops::sync_write(impl.descriptor_, impl.state_,
                                                      bufs.buffers(), bufs.count(), bufs.all_empty(), ec);
                }
            }

            // Wait until data can be written without blocking.
            size_t write_some(implementation_type &impl,
                              const null_buffers &, asio::error_code &ec) {
                // Wait for descriptor to become ready.
                descriptor_ops::poll_write(impl.descriptor_, impl.state_, ec);

                return 0;
            }

            // Start an asynchronous write. The data being sent must be valid for the
            // lifetime of the asynchronous operation.
            template<typename ConstBufferSequence, typename Handler, typename IoExecutor>
            void async_write_some(implementation_type &impl,
                                  const ConstBufferSequence &buffers, Handler &handler,
                                  const IoExecutor &io_ex) {
                bool is_continuation =
                        asio_handler_cont_helpers::is_continuation(handler);

                typename associated_cancellation_slot<Handler>::type slot
                        = asio::get_associated_cancellation_slot(handler);

                // Allocate and construct an operation to wrap the handler.
                typedef descriptor_write_op <ConstBufferSequence, Handler, IoExecutor> op;
                typename op::ptr p = {asio::detail::addressof(handler),
                                      op::ptr::allocate(handler), 0};
                p.p = new(p.v) op(success_ec_, impl.descriptor_, buffers, handler, io_ex);

                // Optionally register for per-operation cancellation.
                if (slot.is_connected()) {
                    p.p->cancellation_key_ =
                            &slot.template emplace<reactor_op_cancellation>(
                                    &reactor_, &impl.reactor_data_,
                                    impl.descriptor_, reactor::write_op);
                }

                ASIO_HANDLER_CREATION((reactor_.context(), *p.p, "descriptor",
                        &impl, impl.descriptor_, "async_write_some"));

                start_op(impl, reactor::write_op, p.p, is_continuation, true,
                         buffer_sequence_adapter<asio::const_buffer,
                                 ConstBufferSequence>::all_empty(buffers));
                p.v = p.p = 0;
            }

            // Start an asynchronous wait until data can be written without blocking.
            template<typename Handler, typename IoExecutor>
            void async_write_some(implementation_type &impl,
                                  const null_buffers &, Handler &handler, const IoExecutor &io_ex) {
                bool is_continuation =
                        asio_handler_cont_helpers::is_continuation(handler);

                typename associated_cancellation_slot<Handler>::type slot
                        = asio::get_associated_cancellation_slot(handler);

                // Allocate and construct an operation to wrap the handler.
                typedef reactive_null_buffers_op <Handler, IoExecutor> op;
                typename op::ptr p = {asio::detail::addressof(handler),
                                      op::ptr::allocate(handler), 0};
                p.p = new(p.v) op(success_ec_, handler, io_ex);

                // Optionally register for per-operation cancellation.
                if (slot.is_connected()) {
                    p.p->cancellation_key_ =
                            &slot.template emplace<reactor_op_cancellation>(
                                    &reactor_, &impl.reactor_data_,
                                    impl.descriptor_, reactor::write_op);
                }

                ASIO_HANDLER_CREATION((reactor_.context(), *p.p, "descriptor",
                        &impl, impl.descriptor_, "async_write_some(null_buffers)"));

                start_op(impl, reactor::write_op, p.p, is_continuation, false, false);
                p.v = p.p = 0;
            }

            // Read some data from the stream. Returns the number of bytes read.
            template<typename MutableBufferSequence>
            size_t read_some(implementation_type &impl,
                             const MutableBufferSequence &buffers, asio::error_code &ec) {
                typedef buffer_sequence_adapter <asio::mutable_buffer,
                MutableBufferSequence> bufs_type;

                if (bufs_type::is_single_buffer) {
                    return descriptor_ops::sync_read1(impl.descriptor_,
                                                      impl.state_, bufs_type::first(buffers).data(),
                                                      bufs_type::first(buffers).size(), ec);
                } else {
                    bufs_type bufs(buffers);

                    return descriptor_ops::sync_read(impl.descriptor_, impl.state_,
                                                     bufs.buffers(), bufs.count(), bufs.all_empty(), ec);
                }
            }

            // Wait until data can be read without blocking.
            size_t read_some(implementation_type &impl,
                             const null_buffers &, asio::error_code &ec) {
                // Wait for descriptor to become ready.
                descriptor_ops::poll_read(impl.descriptor_, impl.state_, ec);

                return 0;
            }

            // Start an asynchronous read. The buffer for the data being read must be
            // valid for the lifetime of the asynchronous operation.
            template<typename MutableBufferSequence,
                    typename Handler, typename IoExecutor>
            void async_read_some(implementation_type &impl,
                                 const MutableBufferSequence &buffers,
                                 Handler &handler, const IoExecutor &io_ex) {
                bool is_continuation =
                        asio_handler_cont_helpers::is_continuation(handler);

                typename associated_cancellation_slot<Handler>::type slot
                        = asio::get_associated_cancellation_slot(handler);

                // Allocate and construct an operation to wrap the handler.
                typedef descriptor_read_op <MutableBufferSequence, Handler, IoExecutor> op;
                typename op::ptr p = {asio::detail::addressof(handler),
                                      op::ptr::allocate(handler), 0};
                p.p = new(p.v) op(success_ec_, impl.descriptor_, buffers, handler, io_ex);

                // Optionally register for per-operation cancellation.
                if (slot.is_connected()) {
                    p.p->cancellation_key_ =
                            &slot.template emplace<reactor_op_cancellation>(
                                    &reactor_, &impl.reactor_data_,
                                    impl.descriptor_, reactor::read_op);
                }

                ASIO_HANDLER_CREATION((reactor_.context(), *p.p, "descriptor",
                        &impl, impl.descriptor_, "async_read_some"));

                start_op(impl, reactor::read_op, p.p, is_continuation, true,
                         buffer_sequence_adapter<asio::mutable_buffer,
                                 MutableBufferSequence>::all_empty(buffers));
                p.v = p.p = 0;
            }

            // Wait until data can be read without blocking.
            template<typename Handler, typename IoExecutor>
            void async_read_some(implementation_type &impl,
                                 const null_buffers &, Handler &handler, const IoExecutor &io_ex) {
                bool is_continuation =
                        asio_handler_cont_helpers::is_continuation(handler);

                typename associated_cancellation_slot<Handler>::type slot
                        = asio::get_associated_cancellation_slot(handler);

                // Allocate and construct an operation to wrap the handler.
                typedef reactive_null_buffers_op <Handler, IoExecutor> op;
                typename op::ptr p = {asio::detail::addressof(handler),
                                      op::ptr::allocate(handler), 0};
                p.p = new(p.v) op(success_ec_, handler, io_ex);

                // Optionally register for per-operation cancellation.
                if (slot.is_connected()) {
                    p.p->cancellation_key_ =
                            &slot.template emplace<reactor_op_cancellation>(
                                    &reactor_, &impl.reactor_data_,
                                    impl.descriptor_, reactor::read_op);
                }

                ASIO_HANDLER_CREATION((reactor_.context(), *p.p, "descriptor",
                        &impl, impl.descriptor_, "async_read_some(null_buffers)"));

                start_op(impl, reactor::read_op, p.p, is_continuation, false, false);
                p.v = p.p = 0;
            }

        private:
            // Start the asynchronous operation.
            ASIO_DECL void start_op(implementation_type &impl, int op_type,
                                    reactor_op *op, bool is_continuation, bool is_non_blocking, bool noop);

            // Helper class used to implement per-operation cancellation
            class reactor_op_cancellation {
            public:
                reactor_op_cancellation(reactor *r,
                                        reactor::per_descriptor_data *p, int d, int o)
                        : reactor_(r),
                          reactor_data_(p),
                          descriptor_(d),
                          op_type_(o) {
                }

                void operator()(cancellation_type_t type) {
                    if (!!(type &
                           (cancellation_type::terminal
                            | cancellation_type::partial
                            | cancellation_type::total))) {
                        reactor_->cancel_ops_by_key(descriptor_,
                                                    *reactor_data_, op_type_, this);
                    }
                }

            private:
                reactor *reactor_;
                reactor::per_descriptor_data *reactor_data_;
                int descriptor_;
                int op_type_;
            };

            // The selector that performs event demultiplexing for the service.
            reactor &reactor_;

            // Cached success value to avoid accessing category singleton.
            const asio::error_code success_ec_;
        };

    } // namespace detail
} // namespace asio

#include "asio/detail/pop_options.hpp"

#if defined(ASIO_HEADER_ONLY)
# include "asio/detail/impl/reactive_descriptor_service.ipp"
#endif // defined(ASIO_HEADER_ONLY)

#endif // !defined(ASIO_WINDOWS)
//   && !defined(ASIO_WINDOWS_RUNTIME)
//   && !defined(__CYGWIN__)
//   && !defined(ASIO_HAS_IO_URING_AS_DEFAULT)

#endif // ASIO_DETAIL_REACTIVE_DESCRIPTOR_SERVICE_HPP
